 <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>进度条</title>
    <style>
        .father {
            width: 150px;
            height: 30px;
            border: 1px solid #e1251b;
            padding: 1px;
            border-radius: 10px;
            margin: 0 auto;
        }
        .son {
            width: 50%;
            height: 100%;
            background-color: #e1251b;
            transition: all .7;
        }
        .father:hover .son {
            width: calc(100% - 10px);
        }
    </style>
</head>
<body>
    <div class="father">
        <div class="son"></div>
    </div>
</body>
</html>